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Zhang B, Glatz A, Aranson IS, Snezhko A. Spontaneous shock waves in pulse-stimulated flocks of Quincke rollers. Nat Commun 2023; 14:7050. [PMID: 37923744 PMCID: PMC10624688 DOI: 10.1038/s41467-023-42633-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 10/16/2023] [Indexed: 11/06/2023] Open
Abstract
Active matter demonstrates complex spatiotemporal self-organization not accessible at equilibrium and the emergence of collective behavior. Fluids comprised of microscopic Quincke rollers represent a popular realization of synthetic active matter. Temporal activity modulations, realized by modulated external electric fields, represent an effective tool to expand the variety of accessible dynamic states in active ensembles. Here, we report on the emergence of shockwave patterns composed of coherently moving particles energized by a pulsed electric field. The shockwaves emerge spontaneously and move faster than the average particle speed. Combining experiments, theory, and simulations, we demonstrate that the shockwaves originate from intermittent spontaneous vortex cores due to a vortex meandering instability. They occur when the rollers' translational and rotational decoherence times, regulated by the electric pulse durations, become comparable. The phenomenon does not rely on the presence of confinement, and multiple shock waves continuously arise and vanish in the system.
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Affiliation(s)
- Bo Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, and Department of Physics, Nanjing University, Nanjing, 210093, China.
| | - Andreas Glatz
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
- Department of Physics, Northern Illinois University, DeKalb, IL, 60115, USA
| | - Igor S Aranson
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Mathematics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Alexey Snezhko
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
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Das D, Saintillan D. On the absence of collective motion in a bulk suspension of spontaneously rotating dielectric particles. SOFT MATTER 2023; 19:6825-6837. [PMID: 37655464 DOI: 10.1039/d3sm00298e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
A suspension of dielectric particles rotating spontaneously when subjected to a DC electric field in two dimensions next to a no-slip electrode has proven to be an ideal model for active matter [Bricard et al., Nature, 2013, 503, 95-98]. In this system, an electrohydrodynamic (EHD) instability called Quincke rotation was exploited to create self-propelling particles which aligned with each other due to EHD interactions, giving rise to collective motion on large length scales. It is natural to question whether a suspension of such particles in three dimensions will also display collective motion and spontaneously flow like bacterial suspensions do. Using molecular dynamics type simulations, we show that dielectrophoretic forces responsible for chaining in the direction of the applied electric field in conventional electrorheological fluids and the counter-rotation of neighboring particles in these chains prevent collective motion in suspensions undergoing spontaneous particle rotations. Our simulations discover that the fundamental microstructural unit of a suspension under Quincke rotation is a pair of counter-rotating spheres aligned in the direction of the electric field. We perform a linear stability analysis that explains this observation.
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Affiliation(s)
- Debasish Das
- Department of Mathematics and Statistics, University of Strathclyde, Livingstone Tower, 26 Richmond Street, Glasgow G1 1XH, UK.
| | - David Saintillan
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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Junot G, Cebers A, Tierno P. Collective hydrodynamic transport of magnetic microrollers. SOFT MATTER 2021; 17:8605-8611. [PMID: 34614055 DOI: 10.1039/d1sm00653c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigate the collective transport properties of microscopic magnetic rollers that propel close to a surface due to a circularly polarized, rotating magnetic field. The applied field exerts a torque to the particles, which induces a net rolling motion close to a surface. The collective dynamics of the particles result from the balance between magnetic dipolar interactions and hydrodynamic ones. We show that, when hydrodynamics dominate, i.e. for high particle spinning, the collective mean velocity linearly increases with the particle density. In this regime we analyse the clustering kinetics, and find that hydrodynamic interactions between the anisotropic, elongated particles, induce preferential cluster growth along a direction perpendicular to the driving one, leading to dynamic clusters that easily break and reform during propulsion.
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Affiliation(s)
- Gaspard Junot
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, Spain.
| | - Andrejs Cebers
- MMML Lab, Department of Physics, University of Latvia, Jelgavas-3, Riga, LV-1004, Latvia
| | - Pietro Tierno
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, Spain.
- Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona, Spain
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, 08028, Barcelona, Spain
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Pradillo GE, Karani H, Vlahovska PM. Quincke rotor dynamics in confinement: rolling and hovering. SOFT MATTER 2019; 15:6564-6570. [PMID: 31360980 DOI: 10.1039/c9sm01163c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The Quincke effect is an electrohydrodynamic instability which gives rise to a torque on a dielectric particle in a uniform DC electric field. Previous studies reported that a sphere initially resting on the electrode rolls with steady velocity. We experimentally find that in strong fields the rolling becomes unsteady, with time-periodic velocity. Furthermore, we find another regime, where the rotating sphere levitates in the space between the electrodes. Our experimental results show that the onset of Quincke rotation strongly depends on particle confinement and the threshold for rolling is higher compared to rotation in the hovering state.
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Affiliation(s)
- Gerardo E Pradillo
- Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Hamid Karani
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.
| | - Petia M Vlahovska
- Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA and Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.
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Hu Y, Vlahovska PM, Miksis MJ. Colloidal particle electrorotation in a nonuniform electric field. Phys Rev E 2018; 97:013111. [PMID: 29448476 DOI: 10.1103/physreve.97.013111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Indexed: 06/08/2023]
Abstract
A model to study the dynamics of colloidal particles in nonuniform electric fields is proposed. For an isolated sphere, the conditions and threshold for sustained (Quincke) rotation in a linear direct current (dc) field are determined. Particle dynamics becomes more complex with increasing electric field strength, changing from steady spinning around the particle center to time-dependent orbiting motion around the minimum field location. Pairs of particles exhibit intricate trajectories, which are a combination of translation, due to dielectrophoresis, and rotation, due to the Quincke effect. Our model provides a basis to study the collective dynamics of many particles in a general electric field.
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Affiliation(s)
- Yi Hu
- Engineering Science and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA
| | - Petia M Vlahovska
- Engineering Science and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA
| | - Michael J Miksis
- Engineering Science and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
We describe a kind of self-propelling motion of bacteria based on the cooperative action of rotating flagella on the surface of bacteria. Describing the ensemble of rotating flagella in the framework of the hydrodynamics with spin, the reciprocal theorem of Stokesian hydrodynamics is generalized accordingly. The velocity of the self-propulsion is expressed in terms of the characteristics of the vector field of flagella orientation and it is shown that the unusually high velocities of Thiovulum majus bacteria may be explained by the cooperative action of the rotating flagella. The expressions obtained enable us to estimate the torque created by the rotary motors of the bacterium and show quantitative agreement with the existing experimental data.
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Affiliation(s)
- M Belovs
- University of Latvia, Zeļļu-23, Rīga LV-1002, Latvia
| | - A Cēbers
- University of Latvia, Zeļļu-23, Rīga LV-1002, Latvia
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Snezhko A. Complex collective dynamics of active torque-driven colloids at interfaces. Curr Opin Colloid Interface Sci 2016. [DOI: 10.1016/j.cocis.2015.11.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Cēbers A. Poiseuille flow of a Quincke suspension. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032305. [PMID: 25314444 DOI: 10.1103/physreve.90.032305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Indexed: 06/04/2023]
Abstract
The controversy of models of dielectric particle suspensions with antisymmetric stress, which predict a nonphysical cusp of the velocity profile in plane Poiseuille flow under the action of the electrical field, is resolved. In the mean-field approximation, the nonlinear kinetic equation is derived for coupled due to the flow translational and rotational motion of the particles. By its numerical solution, it is shown that the velocity profile is smeared due to the translational diffusion of the particles with opposite directions of rotation. The obtained results for the velocity profiles and flow rates as a function of the electric field strength are in qualitative agreement with the existing experimental results.
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Affiliation(s)
- A Cēbers
- University of Latvia, Zeļļu-8, Rīga, LV-1002, Latvia
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